It is known to equip firearm holsters with locking devices that help prevent unwanted and/or unauthorized withdrawal of the firearm. One locking device includes a saddle with engagement protrusions that is automatically biased into engagement with suitable surfaces of the firearm to inhibit withdrawal. The locking device includes an operating lever that extends out the holster and is operable to disengage the protrusions and allow firearm withdrawal. An example of this locking device can be seen in U.S. Patent Application Publication No. 2006/0157520, the contents of which are hereby incorporated by reference in their entirety. This type of locking device has proven very serviceable. However, additional developments and improvements are possible.